Six mistakes mankind keeps making century after century:
Believing that personal gain is made by crushing others;
Worrying about things that cannot be changed or corrected;
Insisting that a thing is impossible because we cannot accomplish it;
Refusing to set aside trivial preferences;
Neglecting development and refinement of the mind;
Attempting to compel others to believe and live as we do. -- Marcus Tullius Cicero

What is morally wrong can never be advantageous, even when it enables you to make some gain that you believe to be to your advantage. The mere act of believing that some wrongful course of action constitutes an advantage is pernicious. -- Marcus Tullius Cicero

Not to know what happened before you were born is to be a child forever. For what is the time of a man, except it be interwoven with that memory of ancient things of a superior age? -- Marcus Tullius Cicero